1. Field of the Invention
This invention is in the field of supports for conveying devices.
2. Description of the Prior Art
Conveyors are employed in various fields to transport objects along a pathway or over a distance. These conveyors typically comprise one of two types, the belt conveyor and the roller conveyor. In the first type, the conveyor includes a continuous belt which extends over rotatable rollers. The rollers are driven by a motor to move the belt and to transport the objects which are supported thereon. The second type of conveyor incorporates rollers which are rotatably mounted on a shaft, the transported objects resting directly upon the rollers. The rollers either depend upon the force of gravity acting on the objects to move the objects down the conveyor line, or the rollers are positively driven by a motor.
A conveyor may be required to support a substantial amount of weight. This may be true, for example, for a conveyor which is used in conjunction with a case-packing machine. In that instance, the conveyor will simultaneously transport a large number of filled containers. A conveyor may also be required to have substantial load capacity if the single items transported thereon are heavy, as when heavy objects or filled boxes are moved by a conveyor.
The rotatable rollers used in both types of conveyors will typically be supported by a shaft which extends through the center of the rollers, perpendicularly to the path along which the objects are moved. Thus, the weight of the objects in a given section of a conveyor will be supported by a limited number of these shafts. The amount of weight supported by any one shaft will depend upon the spacing between the adjacent shafts, and the length of the shaft (the width of the conveyor).
The support requirements place certain practical limits on the usefulness of some conveyor systems. Many of the continuous belt and rotatable roller conveyors employ rollers which are one piece and span the full width of the conveyor. Roller conveyors having full-width rollers are disclosed, for example, in U.S. Pat. Nos. 3,610,406; 3,627,092; and 3,650,375, each issued to Fleischauer et al. The fact that each roller extends the entire width of the conveyor line precludes the possibility of supporting the roller intermediate of its supported ends. This point is made clear in the first two cited patents, in which contact with the rollers intermediate of the supported ends is used as a means to prevent rotation of the rollers and therefore to restrict movement of objects along the top of the rollers. In U.S. Pat. No. 3,610,406, for example, a pivoted linkage is positioned beneath the rollers, one end of the linkage being secured to a sensing roller assembly. Downward displacement of the sensing roller assembly, and therefore of the connected end of the pivoted linkage, results in upward movement of a brake block located at the opposite end of the pivoted linkage. This upward movement causes the brake block to engage some of the other rollers and to stop their rotation. Similarly, U.S. Pat. No. 3,627,092 discloses a braking mechanism which operates by causing a flexible band to frictionally engage the surface of the rotatable rollers to prevent movement thereof.
As indicated, rollers which extend the full width of the conveyor are not supportable intermediate of the ends thereof. As a result, the amount of weight that may be carried by a conveyor of this type is limited. To enable the conveyor to carry a substantial weight, only the size and strength of materials which are employed in the shafts or rollers may be varied for a given conveyor width. In turn, the systems designed for carrying greater amounts of weight will generally require substantially greater amounts of material and expense. Also, there are practical limits on the size and strength of materials which may be used since the rotation of these elements becomes increasingly difficult with the greater sizes. In particular, those which are motor driven will require substantially greater amounts of power, and will be less efficient.
Multiple-roller conveyors utilize a plurality of rollers mounted upon each shaft between the supported ends of the shaft. Intermediate support is even more important for multiple-roller conveyors, since the conveyor does not have the strength of the unitary roller to add to the strength of the shaft. In other words, the rollers in this type of conveyor do not contribute as significantly to the load capacity of the conveyor. The primary control over the support strength is to alter the length and strength of the shafts. As a result, the need has arisen to provide means for supporting the shaft of this type of conveyor intermediate of the supported ends of the shaft.
In U.S. Pat. No. 2,897,953, issued to Namenyi-Katz on Aug. 4, 1959, there is disclosed a conveyor system which utilizes several parallel, co-planar shafts, each shaft having a plurality of cylindrical rollers mounted thereon. The cylindrical rollers are mounted in side-by-side relation and are mechanically driven by pressurized gas acting upon internal vanes of the rollers. U.S. Pat. No. 3,337,023, issued to Kohl et al., on Aug. 22, 1967, discloses a conveyor system which similarly has a plurality of rollers mounted upon each of several shafts. In neither of these patents, however, is there disclosed a means for supporting the shafts intermediate of the normally-supported ends of the shaft, without obstructing the path of objects travelling along the tops of the rollers.
In my U.S. patent application, Ser. No. 467,090, now issued as U.S. Pat. No. 3,951,255, there is disclosed another conveyor having a plurality of rollers on each shaft. The present invention may be used with this and other multiple-roller conveyors to provide increased load capacity for the conveyor.